1. Field of the Invention
The present invention relates to a displaying method utilizing a sub-pixel display technology and arts related thereto.
2. Description of the Related Art
Displaying apparatuses utilizing various types of display devices have been conventionally used. Of such displaying apparatuses, there is, for example, a type such as a color LCD, color plasma display, etc., in which three light-emitting elements each emitting three primary colors R, G and B are disposed in prescribed order to comprise one pixel, the pixels are juxtaposed in the first direction to comprise one line, and a plurality of lines are provided in the second direction orthogonal to the first direction to comprise a display panel.
For example, there are many display devices whose display screen is comparatively narrow and by which it is difficult to provide fine display as in display devices built in cellular telephones, mobile computers, etc. In such display devices, if an attempt is made to display small characters, photographs or complicated pictures, etc., a portion of the image collapses and easily becomes unclear.
In order to improve display sharpness on a narrow display panel, literature (Title: [Sub-pixel Font Rendering Technology]) regarding sub-pixel displaying, that utilizes one pixel consisting of three light-emitting elements of R, G and B, has been laid open on the Internet. The present inventor et al. downloaded and confirmed the literature from the Site (http://grc.com) or its peripheries on Jun. 19, 2000.
Next, a description is given of the technology with reference to FIG. 28 through FIG. 33. The English letter [A] is taken as an example of an image that is displayed.
Here, FIG. 28 is an exemplary of a single line in the case where a single pixel is thus formed of three light-emitting elements. The horizontal direction (that is, the direction along which light-emitting elements of the three primary colors R, G and B are arranged) in FIG. 28 is called the first direction, and the longitudinal direction orthogonal thereto is called the second direction.
In the present specification, there are cases where the first direction is called a “juxtaposing direction”.
Also, the aligning queue of the light-emitting elements is not the order of R, G and B. Another aligning queue may be taken into consideration. However, even if the aligning queue is changed, the prior art and the invention are applicable as well.
And, the single pixel (three light-emitting elements) is arranged in a row in the first direction to comprise a single line. Further, the line is arranged in the second direction to comprise a display panel.
In the sub-pixel technology, an original image is an image shown in, for example, FIG. 29. In this example, the letter [A] is displayed in a region consisting of seven pixels in both horizontal and longitudinal directions. On the contrary, where respective light-emitting elements of R, G and B are regarded as a single pixel in order to provide a sub-pixel display, as shown in FIG. 30, a font that has resolution power three times in the horizontal direction in a region consisting of 21 (=7×3) pixels in the horizontal direction and seven pixels in the longitudinal direction is prepared.
And, as shown in FIG. 31, colors of the respective pixels in FIG. 29 (that is, pixels not existing in FIG. 30 but existing in FIG. 29) are defined. If the letter is merely displayed as it is, color unevenness occurs. Therefore, as shown in FIG. 32(a), a filtering process is carried out on the basis of coefficients (factors). In FIG. 32(a), the coefficients are shown, corresponding to brightness. Coefficients such as 3/9 times for the center target sub-pixel, 3/9 times for the sub-pixels adjacent thereto, and 1/9 times for the sub-pixels further adjacent thereto are multiplied to adjust the brightness of the respective sub-pixels.
Next, referring to FIG. 33, a detailed description is given of these coefficients. In FIG. 33, an [*] indicates that any one of the light-emitting elements of the three primary colors of R, G and B may be acceptable. And, a filtering process is commenced from the first stage at the bottom, and is shifted to the second stage and the third stage in order.
Herein, when shifting from the first stage to the second stage, energy is uniformly collected at any one of the light-emitting elements of the three primary colors R, G and B. That is, the coefficient for the first stage is only ⅓. Similarly, when shifting from the second stage to the third stage, energy is uniformly collected, that is, the coefficient for the second stage is only ⅓.
However, since a target sub-pixel in the third stage can be reached through the center sub-pixel, left sub-pixel and right sub-pixel in the second stage from the center sub-pixel in the first stage, that is, three channels in total, a synthetic coefficient (which is provided by adding the coefficient in the first stage to that in the second stage) of the center sub-pixel in the first stage becomes 1/3 × 1/3 + 1/3 × 1/3 + 1/3 × 1/3 = 3/9.
Also, since there are two channels to reach the target sub-pixel of the third stage from the sub-pixels adjacent to the center sub-pixel of the first stage, the synthetic coefficient of the sub-pixels adjacent to the center sub-pixel of the first stage becomes 1/3 × 1/3 + 1/3 × 1/3 = 2/9.
In addition, since there is only one channel to reach the target sub-pixel of the third stage from the sub-pixels adjacent next to the center sub-pixel of the first stage, the synthetic coefficient of the sub-pixels adjacent next to the center sub-pixel of the first stage becomes 1/3 × 1/3 = 1/9.
By using a filtering process as described above utilizing a feature (the point in which a single pixel consists of three sub-pixels) of a display device, ease in viewing can be improved rather than mere display of pixel precision.
A technology similar to the above is also disclosed in Patent Publication No. WO 00142762, etc.
With these prior arts, there is a premise in that comparatively small graphic objects such as fonts and icons are displayed. And, the filtering process is carried out in terms of one-pixel precision.
On the other hand, as graphic objects, there are objects composed of geometric elements such as a straight line, a curved line, a circle, an ellipse, etc., and a comparatively large object like a bitmap image in addition to the above. In particular, taking note of the features of this type of display device, it is considered that a three-time image is displayed, in which precision in the juxtaposing direction is made three times that of the direction orthogonal to the juxtaposing direction.
The three-time images may be those inputted by a digital camera, scanner, etc., and may also be those to which some processes are applied thereto, or further, may be those artificially produced by various types of graphic editing applications (which may be either raster type or vector type, may be two-dimensional or three-dimensional, and includes computer-graphic applications).